Question: This North American mystery bird is remarkable for several reasons, which I can provide as clues if necessary, especially since this bird may be quite challenging to identify. Can you tell me what is so special about this species? Can you identify this bird's taxonomic family and species?

Response: This is a lark bunting, Calamospiza melanocorys, a medium-sized sparrow that is placed into the taxonomic family, Emberizidae. The emberizids are usually referred to as "buntings" in Europe whilst they are typically known as "sparrows" (also "juncos" and "towhees") in North America. Even though the emberizids superficially resemble the Old World sparrows, the family Passeridae, they are not closely related.

Here's another, perhaps more revealing, look at the same individual:

Lark buntings are birds of shortgrass prairies, so unfortunately, their numbers are declining due to loss of habitat. These birds eat seeds and insects. Similar to the Eurasian skylark, which also occupy prairies with few or no trees, male lark buntings perform a courtship flight whilst singing.

Here is an adult male lark bunting in breeding plumage, standing on a fencepost:

I think the bird in our mystery bird photograph is a female lark bunting. Even though the males of this strongly dimorphic species do adopt a drab winter plumage, they still are somewhat more colourful than the female: a male has brighter buff-coloured wing-patches, his head and back is more reddish in colour, and the feathers on his abdomen are black underneath (although you can't see this in the mystery bird photograph).

Here's a recent vagrant lark bunting in winter plumage that turned up in Massachusetts (filmed on 10 October 2011; you may wish to turn the sound down):

Female lark buntings can be confused with female chestnut-collared and McCown's longspurs, but the lark bunting's streakier underparts and much shorter wings that barely reach the base of the tail are distinctive.

There are several things that are remarkable about this species. First, as you saw in the first embedded video, male lark buntings in breeding plumage are distinctive: they are a gorgeous jet black with white wing patches. This plumage is replaced with a drab grayish brown winter plumage resembling that worn by the noticeably smaller female. Since the lark bunting is the only bird with a plain winter plumage, that makes this species special amongst sparrows, in my opinion.

Second, the lark bunting is monotypic, signifying that these birds have no known close relatives and that they are significantly different from other species in their taxonomic family.

Apparently, other people think this bird is special, too: in 1931, the lark bunting chosen to be the state bird of Colorado.